Optical fiber cables used in the field of inter-connection are directed to general users, and, therefore, used under a severer environment than an environment in which trunk optical fiber cables are used. For example, assuming that an optical fiber cable is bent at an angle close to 180°, the optical fiber cable is required to have rupture resistance that optical fibers inside the optical fiber cable are less likely to rupture even if the optical fiber cable is bent with a small bending radius of, for example, 1.5 mm to 2 mm.
To obtain favorable rupture resistance, it is effective to make a glass diameter of the optical fiber smaller. Because the glass diameter of the optical fiber is typically 125 μm, if a thin optical fiber having a glass diameter of less than 125 μm is used, the rupture resistance is improved (see, for example, Japanese Patent No. 3518089 and the specification of U.S. Pat. No. 8,189,978).